China and Japan exchange mutual attacks over disputed gas field

Foreign minister Katsuya Okada Friday confirmed that Japan had seen the ship transports several days ago, and had repeatedly inquired Beijing about them through diplomatic channels, according to an Agence-France Presse report.

Okada reportedly made the statement before he stepped down, as part of a cabinet reshuffle in Japan, MarketWatch reports.

Tensions between the countries have heightened since Japan arrested the captain of a Chinese fishing boat that collided with the Japanese coast guard this month.

If China drills, Japan may also test drill in a nearby area, the report said, according to Bloomberg.